1. Field of the Invention
This invention relates to apparatus for securely selecting data pathways in an encryption or decryption system, and in particular to securely routing encryption or decryption keys in a pay-television system.
2. Description of the Related Art
The use of encryption techniques in subscriber-based systems is essential to prevent unauthorized access to broadcasts by parties who are not entitled to access them. For example, a person may wish to gain access to a sports broadcast service without making the appropriate payment to the broadcast service provider.
Many encryption techniques make use of secret electronic keys to encrypt broadcast data so that the data can only be comprehended when decrypted using a specified key possessed by a subscriber. In a typical system, various keys are provided for different encryption operations which need to be securely routed along with other data to or from various internal memories or other external sources or destinations.
We have appreciated that it is important to ensure that encryption or decryption keys and other confidential data are not intercepted otherwise the security of the system may be jeopardised. In prior software-based systems, processors running computer programs are used to control data routing. Such systems are vulnerable to hacking when computer code is modified causing sensitive data to be routed to insecure data destinations where the hacker is able to obtain it. We have also appreciated the need for a means to securely control the routing of encryption keys.